Field of the Invention
The present invention relates to a microprogrammable control unit in which a microprogram is stored in a memory and comprises a plurality of command words, in which the addresses of the command words are stored in an address register connected to the memory, and in which control signals for a switching unit which is to be controlled are produced by means of decoders connected to the memory, and in which conditions in the switching unit can be interrogated by means of multiplexers.
Description of the Prior Art
It is already generally well known in the art to execute control functions in switching units with the aid of microprocessors. Microprocessors of this type represent relatively efficient control computers which are accommodated in one or more than one integrated module. However, because of the technology employed, generally MOS technology, such microprocessors have long command times, and consequently are unsuitable for control functions in which a short command sequence time is required.
An analysis of the functions to be assumed by a microprogram-controlled switching unit indicates that it is not necessary in every case for the switching unit to execute arithmetic functions, such as, for example, addition or subtraction, as facilitated by currently available microprocessors with the aid of a widely fanned set of commands. However, in most cases it is not possible to eliminate the interrogation of variable states in the switching unit which is to be controlled and it is not possible to eliminate a change in the states of the controlled switching unit in dependence upon interrogated conditions. Furthermore, logical links of the interrogated conditions may also be necessary.